Method of forming a strip having substantially differing thicknesses

ABSTRACT

A method of forming a strip having substantially differing thicknesses including a wide thinner section adjacent one edge and a thicker section adjacent the thinner section. The wide thinner section is formed by first rolling a longitudinal depressed indentation in the section of strip which will later be formed into the thinner section while providing an edge material portion between the indentation and the edge of the strip. Thereafter the strip is further rolled to further reduce the indentation and to reduce the edge material portion to form the thinner section.

United States Patent [191 Bray et al.

[4 1 Mar. 11, 1975 METHOD OF FORMING A STRIP HAVING SUBSTANTIALLY DIFFERING THICKNESSES [75] Inventors: Robert S. Bray; Claude D. Tapley,

both of Cheshire, Conn.

[73] Assignee: Anaconda American Brass C0., Waterbury, Conn.

22 Filed: Sept. 24, 1973 21 Appl. No.: 400,228

FOREIGN PATENTS OR APPLICATIONS 360,767 10/1922 Germany 72/366 Primary Examiner-Lowell A. Larson Attorney, Agent, or Firm-Pennie & Edmonds [57] ABSTRACT A method of forming a strip having substantially differing thicknesses including a wide thinner section adjacent one edge and a thicker section adjacent the thinner section. The wide thinner section is formed by first rolling a longitudinal depressed indentation in the section of strip which will later be formed into the thinner section while providing an edge material portion between the indentation and the edge of the strip. Thereafter the strip is further rolled'to further reduce the indentation and to reduce the edge material portion to form the thinner section.

3 Claims, 3 Drawing Figures PATENTEDHARI 1 MS 9.999.999

FIG. 2

FIG. 3

METHOD OF FORMING A STRIP HAVING SUBSTANTIALLY DIFFERING THICKNESSES BACKGROUND OF THE INVENTION The rolling of metal strips to form a section thinner than the remainder of the strip has not presented substantial problems where the width of thinner section was not a substantial portion of the entire width of the strip. As the width of the thinner section was increased, problems in forming a strip of desired straightness and dimensional accuracy were experienced. For example, the step rolling technique of U.S. Pat. No. 3,488,989 to Rakich et al. entitled Method of Producing Dual Gauge Strip," which patent is owned by the assignee of the present application, has been found ineffective in some applications requiring wide thinner sections.

The present invention provides a double rolling technique using two sets of rollers each having different engaging configurations. Through the use of two rolling operations and through the design of the rollers, as herein described, a wide thinner section can be readily rolled as part of the strip.

SUMMARY OF THE INVENTION Broadly, the present invention comprises a two pass forming operation in which the stock strip of generally rectangular configuration is rolled to form an indentation in a portion of the strip adjacent a strip edge while leaving an edge material portion raised above the indentation between said strip edge and the indentation. The first pass is followed by a second pass which flattens the edge material portion and further reduces the indentation to form a wide thinner section of generally uniform thickness. The strip, as formed in such steps, has also a portion adjacent the thinner portion which is thicker than the thinner portion.

It is a feature of the present invention that the thinner section can be rolled to accurate dimensions.

It is a further feature of the invention that a strip can be rapidly fabricated without any machining operation being required.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of a stock strip usable in the practice of the invention;

FIG. 2 is a sectional view of the stock strip after the first pass operation; and

FIG. 3 is a sectional view of the strip after the second pass operation.

A DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIGS. 1, 2 and 3 of the drawings, strip 1 is a copper-bearing rectangular cross-sectional stock material which is suitable for shaping and forming using rolling techniques. Other metal strips capable of being shaped by rolling mills used in industry may also be used.

Strip 1 is first passed through a pair of opposed rolls shaped and positioned to reduce the thicknesses of left hand section 2 (as viewed in FIG. 1) and to simulta- I neously form in the right hand section 3 a depression or indentation 4. The reduced thickness area 5 positioned below indentation 4 has a surface generally parallel to lower surface profile 6 of the strip. During the first pass, there is formed in section 3 between depressed indentation 4 and the strip edge 7 an edge material portion 8. Portion 8 provides a reservoirof material for distribution at and near the edge area of section 3 during the second rolling operation and provides an important part of the present invention. Portion 8 assists in rapid and effective material distribution during the second rolling operation. Stepped rollers are used in the second pass to form the configuration shown in FIG. 3 including formed thicker portion 10 and formed thinner portion 11.

In the preferred practice of the invention, the overall width of the strip is increased with each reduction and thicker portion 2 is also reduced in each pass. The shape of the depressed indentation 4 may be varied through a vertically oriented ledge 12 defining the inner end portion of the indentation is preferred. The sloping outer end portion 13 of the indentation may alternatively be vertically disposed, if desired, or disposed at any other suitable angle.

The strip, after being rolled to the configuration of FIG. 3, may be cut up into short lengths of an inch or less and used as an electrical connectors or lead frames. The strip of FIG. 3 may be further rolled and shaped using conventional stepped rollers if reduced dimensions are desired.

Success in obtaining good dimensioning has been achieved in a configuration having an overall width of 0.875 inches, a 0.05 inch formed thicker portion, a 0.025 inch thinner portion and a thinner portion having a 0.325 inch width (see FIG. 3). The thinner portion is a wide portion in relationship to the overall width of the strip in that, absent the two step forming methods herein disclosed, it would be difficult or impossible to form the thinner section with the desired dimensions demanded by industry for certain electrical and electronic uses. A wide thinner section is one that would cause rolling problems using prior methods and includes in most cases a width more than one third of the overall width of the formed strip. The thinness of the formed thinner portion of the strip is illustrated through the dimensions and proportions set forth in this paragraph.

We claim:

1. A method of continuous roll forming an elongated strip having a generally-rectangular cross-sectional area to form a strip with a cross-sectional area including a formed thicker portion and a wide formedthinner portion comprising a. rolling the generally-rectangular strip to initially form an intermediate configuration having a thicker portion which is less thick than the generally-rectangular strip and a thinner portion which thinner portion has no thickness as great as the thicker portion and having a longitudinal depression positioned in the thinner portion and spaced from the outer edge of the strip to thereby form an edge material portion having a thickness greater than the remainder of the thinner portion;

b. further rolling both thicker and thinner portions of the strip to reduce the thickness of the thicker portion and to reduce the thickness of the intermediate thinner portion while at the same time reducing the edge material portion to a thickness desired for the formed thinner portion thereby forming a strip having a formed thicker portion and formed thinner portion.

outer edge of the strip, the upper surface of the strip and a sloping portion extending down from the upper surface to the depression surface of the thinner section. 

1. A method of continuous roll forming an elongated strip having a generally-rectangular cross-sectional area to form a strip with a cross-sectional area including a formed thicker portion and a wide formed thinner portion comprising a. rolling the generally-rectangular strip to initially form an intermediate configuration having a thicker portion which is less thick than the generally-rectangular strip and a thinner portion which thinner portion has no thickness as great as the thicker portion and having a longitudinal depression positioned in the thinner portion and spaced from the outer edge of the strip to thereby form an edge material portion having a thickness greater than the remainder of the thinner portion; b. further rolling both thicker and thinner portions of the strip to reduce the thickness of the thicker portion and to reduce the thickness of the intermediate thinner portion while at the same time reducing the edge material portion to a thickness desired for the formed thinner portion thereby forming a strip having a formed thicker portion and formed thinner portion.
 1. A method of continuous roll forming an elongated strip having a generally-rectangular cross-sectional area to form a strip with a cross-sectional area including a formed thicker portion and a wide formed thinner portion comprising a. rolling the generally-rectangular strip to initially form an intermediate configuration having a thicker portion which is less thick than the generally-rectangular strip and a thinner portion which thinner portion has no thickness as great as the thicker portion and having a longitudinal depression positioned in the thinner portion and spaced from the outer edge of the strip to thereby form an edge material portion having a thickness greater than the remainder of the thinner portion; b. further rolling both thicker and thinner portions of the strip to reduce the thickness of the thicker portion and to reduce the thickness of the intermediate thinner portion while at the same time reducing the edge material portion to a thickness desired for the formed thinner portion thereby forming a strip having a formed thicker portion and formed thinner portion.
 2. The method of claim 1 in which the width of formed thinner portion is one third as wide as the overall strip width. 